2.6. JC-1
Mitochondrial membrane potential (∆Ψm) was measured using the JC-1 mitochondrial membrane potential assay kit (Beyotime Institute of Biotechnology, Beijing, China). The cells were incubated with JC-1 working dye for 20 min, washed twice with cold JC-1 staining buffer, and visualized under a fluorescence microscope (DMI4000B; Leica, Wetzlar, Germany).